$ perl -le"sub Yoda::Says { warn join q/  / , @_ };  q{Yoda::Says}->( q/hello/ ) ; "
hello at -e line 1.

$ perl -le"sub Yoda::Says { warn join q/  / , @_ };  q{Yoda::&Says}->( q/hello/ ) ; "
Undefined subroutine &Yoda::&Says called at -e line 1.